Distribution characteristics of coal reservoir permeability under the action of tectonic movement in western Fukang mining area

Finding out the characteristics of permeability distribution of a small-scale coal reservoir can provide important guarantee for reasonable wells pattern deployment and scientific prediction of productivity. Based on observation, statistics and assorting of the joints of coal or rock in western Fukang mining area, the main tectonic stress directions in late Yanshan period, the early and late Himalayan were obtained. The characteristics of permeability distribution of coal reservoir in 14 blocks after multiple tectonic movements were obtained using tectonic movement inversion method and coal seam stress difference analysis method. The results showed that the heterogeneity of coal reservoir permeability in small scale is obvious because of the influence of multiphase tectonic movements.The coal structure of shallow seam located in the raising end of synclinal axis is mainly primary and cataclastic, and the permeability is best in study area. In northestern oxidizing zone and south wing of the study area, the deformation of coal seam is weak, and the permeability is medium. The blocks near another end of the synclinal axis where the buried depth of coal seam is deep, were greatly influenced by the multiphase tectonic movements, coal structure is mainly mylonitic and broken, the permeability is low. The blocks in the south and the northwest of study area were affected the most greatly by multiphase tectonic movements, the permeability is the lowest. The accuracy of prediction results was verified by drilling coring and permeability data. The results can provide thinking and reference for prediction of coalbed permeability in a small area affected by multiphase tectonic movements.